1. Field of the Invention
The present invention relates to a resin-coated steel sheet for drawn and ironed cans, and a drawn and ironed can manufactured therefrom.
2. Description of the Related Art
Japanese Laid-open Patent Application No. Sho-60-168643 discloses a resin coated steel sheet for drawn and ironed cans (hereinafter referred to as "DI cans") which is excellent in workability in drawing and ironing and which enables a high degree of ironing (an ironing ratio of 60% or higher) with a resin film being kept coated on the inside face of the can, and which gives, by drawing and ironing, DI cans satisfactory in resin film adhesion, corrosion resistance, and external appearance.
The resin-coated steel sheet disclosed in the above Laid-open Patent Application comprises (1) a coating layer of a thermoplastic resin such as a polyethylene terephthalate resin, being capable of orienting and having a barrier property against corrosive components, the layer being provided on one side of the steel sheet, which side forms an inside face of the DI cans; (2) an inorganic oxide film layer such as of chromium hydrate oxide provided under the coating layer as an adhering undercoating; and (3) a metal coating layer of ductile metal such as tin provided on the other side of the steel sheet which forms the outside face of the DI cans.
In order to manufacture a DI can which has a resin coating satisfactory in adhesion, corrosion resistance, and external appearance, as described in the above Laid-open Patent Application, the coating resin of the resin-coated steel sheet for DI cans is required to be brought to a suitable drawing temperature in the drawing and ironing step, (the suitable temperature being lower than the crystallization temperature of the resin, and within the range of the glass-transition temperature (T.sub.g) .+-.30.degree. C., e.g., 40 to 100.degree. C. for a PET resin. Since the resin-coated steel sheets, which are produced by a known extrusion-lamination method (T-die method) and subjected to the drawing and ironing, are usually stored at a normal temperature, a preheating process for the resin-coated steel sheets is required, disadvantageously adding to the conventional can-manufacturing process.